CN114787305A - Two-part (2K) curable adhesive composition - Google Patents

Abstract

The present invention relates to a curable and debondable two part (2K) adhesive composition comprising: i) a first portion comprising: (meth) acrylate ester monomers; a copolymerizable acid; and an electrolyte; and, ii) a second part comprising: a first curing agent for the first part of monomers; a second curing agent for the monomers of the first part; and a solubilizer.

Description

Two-part (2K) curable adhesive composition

Technical Field

The present invention relates to an adhesive composition that can be debonded from the particular substrate to which it is applied. More particularly, the present invention relates to two-part (2K) curable and debondable adhesive compositions.

Background

Adhesive bonds and polymer coatings are commonly used for assembly and finishing of finished products. They are used in place of mechanical fasteners such as screws, bolts and rivets to provide bonding with reduced tooling costs and greater flexibility in the manufacturing process. The adhesive bond distributes stress evenly, reduces the likelihood of fatigue and seals the joint from corrosive substances.

While adhesive bonding thus provides many advantages over mechanical fasteners, it is often difficult in practical applications to remove adhesively bonded objects. Removal of the adhesive by mechanical processes (e.g., by sandblasting or by wire brush cleaning) is generally precluded, in part, because the adhesive is located between the substrates and is therefore difficult to access or abrade without damaging the substrate surface. Disassembly by use of chemicals and/or high temperatures, such as disclosed in U.S. patent No. 4,171,240 (Wong) and U.S. patent No. 4,729,797 (Linde et al), can be effective, but can be time consuming and complex to perform: in addition, the corrosive chemicals and/or harsh conditions required may damage the substrate being separated, making it unsuitable for subsequent use.

In view of these problems, some authors have attempted to develop debondable adhesive compositions in which the passage of current through the cured composition serves to break the bond at the interface of the adhesive and the substrate.

U.S. patent No. 7,465,492 (Gilbert) describes a debondable composition comprising: a matrix functional group comprising a monomer selected from the group consisting of acrylic, methacrylic, and combinations thereof; a free radical initiator; and an electrolyte, wherein the electrolyte provides sufficient ionic conductivity to the composition to support faradaic reactions at bonds formed between the composition and a conductive surface and thereby allow debonding of the composition from the surface.

US 2007/0269659(Gilbert) describes an adhesive composition which is debondable at two interfaces, the composition: (i) comprising a polymer and an electrolyte; (ii) facilitating the joining of two surfaces; (iii) debonding from the anode and cathode surfaces occurs in response to a voltage applied across the two surfaces to form an anode interface and a cathode interface.

US 2008/0196828(Gilbert) describes a hot melt adhesive composition comprising: a thermoplastic component; and an electrolyte, wherein the electrolyte provides sufficient ionic conductivity to the composition to undergo faradaic reactions at bonds formed between the composition and a conductive surface and to allow debonding of the composition from the surface.

WO 2017/133864(Henkel AG & co. kgaa) describes a method of reversibly bonding a first substrate and a second substrate, wherein at least the first substrate is a non-conductive substrate, the method comprising: a) coating the surface of one or more non-conductive substrates with a conductive ink; b) applying an electrically debondable hot melt adhesive composition to the conductive ink coated surface of the first substrate and/or the second substrate; c) contacting the first substrate with a second substrate such that the electrically debondable hot melt adhesive composition is sandwiched between the two substrates; d) forming an adhesive bond between two substrates to provide an adhered substrate; and e) applying a voltage to the bonded substrate, whereby the adhesion of at least one interface between the electrically debondable hot melt adhesive composition and the substrate surface is substantially weakened.

There remains a need in the art to provide an adhesive composition that can be conveniently applied to the surfaces of substrates to be bonded, that can provide effective bonding within a composite structure containing the substrates after curing, but that can be effectively debonded from those substrates by the easy application of an electrical potential across the cured adhesive.

Disclosure of Invention

According to a first aspect of the present invention there is provided a curable and debondable two part (2K) adhesive composition comprising:

a first portion comprising:

(meth) acrylate ester monomers;

a copolymerizable acid; and

an electrolyte; and

a second part comprising:

a first curing agent for the monomers of the first part;

a second curing agent for the monomers of the first part; and

a solubilizer.

The adhesive composition may further comprise conductive particles, in particular carbon black and silver particles, which may be disposed in one or both of the first and second portions thereof.

In an important embodiment of the present invention, the two-part adhesive composition comprises:

a first portion comprising, based on the weight of the first portion:

20 to 80 wt%, preferably 40 to 75 wt% of the (meth) acrylate ester monomer;

0.25 to 20 wt%, preferably 6 to 16 wt% of the copolymerizable acid; and

2.5 to 25 wt%, preferably 4 to 23 wt% of the electrolyte; and

a second part comprising, based on the weight of the second part:

25 to 75 weight percent of the first curing agent;

0.01 to 5 wt%, preferably 0.03 to 1 wt% of the second curing agent; and

from 20 to 45% by weight, preferably from 28 to 40% by weight, of the solubilizer.

In the first part of the adhesive composition, the copolymerizable acid is preferably selected from the group consisting of methacrylic acid, acrylic acid, itaconic acid, maleic acid, aconitic acid, crotonic acid, fumaric acid, and mixtures thereof; note that methacrylic acid is particularly preferable.

Independently of or in addition to this preferred statement to the copolymerizable acid of the first part, the electrolyte is preferably selected from the group consisting of 1-ethyl-3-methylimidazolium methanesulfonate, 1-ethyl-3-methylimidazolium methylsulfate, 1-hexyl-3-methylimidazolium 2- (2-fluoroanilino) -pyridinium, 1-hexyl-3-methylimidazolium imide, 1-butyl-1-methyl-pyrrolidinium 2- (2-fluoroanilino) -pyridinium, 1-butyl-1-methyl-pyrrolidinium imide, trihexyl (tetradecyl) phosphonium 2- (2-fluoroanilino) -pyridinium, cyclohexyltrimethylammonium bis (trifluoromethylsulfonyl) imide, bis (2-hydroxyethyl) ammonium trifluoroacetate, N-dimethyl (2-hydroxyethyl) ammonium octanoate, methyltrioctylammonium bis (trifluoromethylsulfonyl) imide, N-Ethyl-N-N-N-tetramethylguanidine trifluoromethanesulfonate, guanidine trifluoromethanesulfonate, 1-butyl-4-methylpyridinium bromide, 1-butyl-3-methylpyridinium tetrafluoroborate, 1-butyl-3-hydroxymethylpyridinium ethyl sulfate, 1-butyl-1-methylpyrrolidinium bis (trifluoromethylsulfonyl) imide, 1-butyl-methylpyrrolidinium tris (pentafluoroethyl) trifluorophosphate, 3-methylimidazolium ethyl sulfate, 1-ethyl-3-methylimidazolium chloride, 1-ethyl-3-ethyl-methylimidazolium bromide, 1-butyl-3-methylimidazolium chloride, 1-hexyl-3-methylimidazolium chloride, 1-octyl-3-methylimidazolium chloride, 1-methyl-3-octylimidazolium chloride, 1-propyl-3-methylimidazolium iodide, 1-hexyl-3-methylimidazolium iodide, 1-butyl-3-methylimidazolium tetrafluoroborate, 1-butyl-3-methylimidazolium trifluoromethanesulfonate, 1-butyl-3-methylimidazolium hexafluorophosphate, 1-butyl-2, 3-dimethylimidazolium tetrafluoroborate, 1-butyl-2, 3-dimethylimidazolium hexafluorophosphate, 1-butylimidazole, 1-methylimidazolium tetrafluoroborate, tetrabutylphosphonium tris (pentafluoroethyl) trifluorophosphate, trihexyl (tetradecyl) phosphonium tetrafluoroborate and mixtures thereof. Particularly preferably used is at least one of 1-ethyl-3-methylimidazolium methanesulfonate and 1-ethyl-3-methylimidazolium methylsulfate.

In the second part of the adhesive composition, it is preferred that the first curing agent is a peroxide curing agent preferably selected from the group consisting of: t-butyl peroxide, t-butyl perbenzoate, cumene hydroperoxide, t-butyl perbenzoate, diacetyl peroxide, benzoyl peroxide, t-butyl peracetate, lauroyl peroxide, and mixtures thereof; benzoyl peroxide is particularly preferably used.

Independently of or in addition to this preferred statement regarding the first curing agent, the second curing agent preferably consists of at least one compound which is a salt or complex of a transition metal selected from the group consisting of Fe, Co, V, Mn and Cu. More preferably, the second curing agent comprises or consists of at least one iron-based compound selected from ferrocene, iron (II) acetylacetonate, iron (III) ammonium hexa (cyano-C) ferrate; note that ferrocene is particularly preferred.

Independently of or in addition to the preferred statements made for the first and second curing agents, it is preferred that the solubilizer of the second part of the adhesive composition is a polyethylene glycol or an epoxy resin selected from the group consisting of: cycloaliphatic epoxides, epoxy novolac resins, bisphenol a epoxy resins, bisphenol F epoxy resins, bisphenol a epichlorohydrin based epoxy resins, alkyl epoxides, limonene dioxide, polyepoxides, and mixtures thereof; particular preference is given to solubilizers which comprise or consist of bisphenol A epoxy resins.

According to a second aspect of the present invention, there is provided an adhesive structure comprising:

a first layer of material having a conductive surface; and

a second layer of material having a conductive surface,

wherein a cured debondable two part (2K) adhesive composition as defined above and in the appended claims is disposed between the first and second material layers.

According to a third aspect of the present invention, there is provided a method of debonding the adhesive structure as defined above and in the appended claims, the method comprising the steps of:

i) applying a voltage across the two surfaces to form an anode interface and a cathode interface; and

ii) debonding the surface.

Step i) of the method is preferably characterized by at least one of the following:

a) an applied voltage of 0.5 to 100V; and

b) the voltage is applied for a duration of 1 second to 60 minutes.

Definition of

As used herein, the singular forms "a", "an" and "the" include plural referents unless the context clearly dictates otherwise.

As used herein, the terms "comprising," "comprises," and "comprising" are synonymous with "including," "includes," "containing," "contains," or "containing," and are inclusive or open-ended and do not exclude other, non-recited members, elements, or method steps.

As used herein, the term "consisting of … …" excludes any element, ingredient, member or method step not specified.

When amounts, concentrations, dimensions, and other parameters are expressed as ranges, preferred ranges, upper values, lower values, or preferred upper and lower values, it is to be understood that any range that is obtainable by combining any upper value or preferred value with any lower value or preferred value, regardless of whether the range so obtained is explicitly recited in the context.

Furthermore, according to standard understanding, the weight range denoted "0 to x" specifically includes 0 wt%: the ingredients defined by the ranges may be absent from the composition or may be present in the composition in an amount up to x weight percent.

The words "preferred," "preferably," "ideally," and "particularly" are used generically to refer to embodiments of the disclosure that may provide particular benefits in certain circumstances. However, the recitation of one or more preferred, ideal, or particular embodiments does not imply that other embodiments are not useful, and is not intended to exclude those other embodiments from the scope of the disclosure.

The word "may" as used in this application is used in a permissive sense, i.e., meaning having the potential to, rather than the mandatory sense.

As used herein, room temperature is 23 ℃. + -. 2 ℃. As used herein, "ambient conditions" refers to the temperature and pressure of the environment in which the composition is or in which the coating or substrate of the coating is located.

By "two-part (2K) composition" in the context of the present invention is understood a composition wherein the first part (a) and the second part (B) have to be stored in separate containers due to their (high) reactivity. The two parts are mixed only shortly before application and then reacted, usually without additional activation, to form a bond, thereby forming a polymer network. Higher temperatures may be used here to accelerate the crosslinking reaction.

As used herein, the term "debondable" means that the bond strength may decrease by at least 50% after the adhesive is cured after application of a potential of 10V to 75V for a duration of 1 second to 60 minutes. Applying the cured adhesive between two substrates bonded by the adhesive such that an electrical current flows through the adhesive bond line. The adhesive strength is measured by the Tensile Lap Shear (TLS) test carried out at room temperature and is Based on the Determination of the tensile lap shear strength of adhesive-bonded assemblies (Based on Adhesives-Determination of tensile lap-shear of bonded assemblies) in accordance with EN 1465:2009 (german edition). The bond overlap area was 25mm x 10mm and the bond thickness was about 150 μm.

As used herein, the term "monomer" refers to a substance that can undergo a polymerization reaction to contribute structural units to the chemical structure of a polymer. As used herein, the term "monofunctional" means having one polymerizable moiety. As used herein, the term "multifunctional" refers to having more than one polymerizable moiety.

As used herein, the term "equivalent (eq.)" relates to the relative number of reactive groups present in a reaction, as is usual in chemical notation.

The term "electrolyte" is used herein according to its standard meaning in the art as a substance containing free ions that can conduct electricity by displacement of a charged carrier substance. The term is intended to encompass molten electrolytes, liquid electrolytes, semi-solid electrolytes, and solid electrolytes in which at least one of the cationic or anionic components of their electrolyte structure is not substantially displaced and thus acts as a charge carrier.

The curable adhesive composition of the invention and the cured adhesive obtained therefrom have an "electrolyte function" in that the adhesive material allows conduction of ions, anions, cations or both anions and cations. The electrolyte function is understood to result from the ability of the composition and the cured binder to solvate at least one polar ion.

As used herein, "(meth) acryl" is a shorthand term for "acryl" and/or "methacryl". Thus, the term "(meth) acrylamide" refers collectively to acrylamide and methacrylamide.

As used herein, "C₁-C_nAn alkyl "group refers to a monovalent group containing 1 to n carbon atoms, which is a radical of an alkane and includes straight and branched chain organic groups. As such, "C₁-C₃₀An alkyl "group refers to a monovalent group containing 1 to 30 carbon atoms, which is a radical of an alkane and includes both straight and branched chain organic groups. Examples of alkyl groups include, but are not limited to: methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, n-hexyl, n-heptyl and 2-ethylhexyl. In the present invention, such alkyl groups may be unsubstituted or may be substituted with one or more substituents, such as halogen, nitro, cyano, amido, amino, sulfonyl, sulfinyl, sulfanyl, sulfoxy, urea, thiourea, sulfamoyl, sulfonamide, and hydroxyl. Where applicable, the preferences for a given substituent will be noted in the specification. Then, it is generally noted that an alkyl group (C) having 1 to 18 carbon atoms is preferred₁-C₁₈Alkyl), for example, an alkyl (C) group having 1 to 12 carbon atoms₁-C₁₂Alkyl) or alkyl (C) containing 1 to 6 carbon atoms₁-C₆Alkyl groups).

As used herein, the term "C₁-C₁₈Hydroxyalkyl "refers to a HO- (alkyl) group having 1 to 18 carbon atoms, wherein the point of attachment of the substituent is through an oxygen atom and the alkyl group is as defined above.

"alkoxy" means a monovalent group represented by-OA, whichWherein A is an alkyl group: non-limiting examples thereof are methoxy, ethoxy and isopropoxy. As used herein, the term "C₁-C₁₈Alkoxyalkyl "refers to an alkyl group having an alkoxy substituent as defined above, and wherein the (alkyl-O-alkyl) moiety contains a total of from 1 to 18 carbon atoms: such groups include methoxymethyl (-CH)₂OCH₃) 2-methoxyethyl (-CH)₂CH₂OCH₃) And 2-ethoxyethyl.

As used herein, the term "C₂-C₄Alkylene "is defined as a saturated divalent hydrocarbon radical having 2 to 4 carbon atoms.

The term "C₃–C₃₀Cycloalkyl "is understood to mean an optionally substituted, saturated, monocyclic, bicyclic or tricyclic hydrocarbon radical having from 3 to 30 carbon atoms. In general, it is noted that cycloalkyl groups (C) having 3 to 18 carbon atoms are preferred₃-C₁₈Cycloalkyl). Examples of cycloalkyl groups include: cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, adamantane, and norbornane.

As used herein, "C" alone or as part of a larger moiety as in "aralkyl" is used₆-C₁₈An aryl "group refers to optionally substituted monocyclic, bicyclic, and tricyclic ring systems, wherein the monocyclic ring system is aromatic or at least one of the rings in the bicyclic or tricyclic ring system is aromatic. Bicyclic and tricyclic ring systems include benzo-fused 2-3 membered carbocyclic rings. Exemplary aryl groups include: a phenyl group; (C)₁-C₄) Alkylphenyl groups such as tolyl and ethylphenyl; an indenyl group; naphthyl, tetrahydronaphthyl, tetrahydroindenyl; a tetrahydroanthracenyl group; and, an anthracene group. And it can be noted that phenyl is preferred.

As used herein, "C" is₂-C₂₀Alkenyl "refers to a hydrocarbon group having 2 to 20 carbon atoms and at least one ethylenically unsaturated unit. The alkenyl group may be linear, branched or cyclic, and may be optionally substituted. As understood by those of ordinary skill in the art, the term "alkenyl" also includes alkenyl groups having the "cis (cis)" and "trans (trans)" configurations, or "E" and "Z"A group of configuration. However, it should generally be noted that it is preferable to contain 2 to 10 (C)_2-10) Or 2 to 8 (C)_2-8) Unsubstituted alkenyl of carbon atoms. Said C is₂-C₁₂Examples of alkenyl groups include, but are not limited to: -CH₂、–CH–CHCH₃、–CH₂CH–CH₂、–C(–CH₂)(CH₃)、–CH–CHCH₂CH₃、–CH₂CH–CHCH₃、–CH₂CH₂CH–CH₂、–CH–C(CH₃)₂、–CH₂C(–CH₂)(CH₃)、–C(–CH₂)CH₂CH₃、–C(CH₃)–CHCH₃、–C(CH₃)CH–CH₂、–CH–CHCH₂CH₂CH₃、–CH₂CH–CHCH₂CH₃、–CH₂CH₂CH–CHCH₃、–CH₂CH₂CH₂CH–CH₂、–C(–CH₂)CH₂CH₂CH₃、–C(CH₃)–CHCH₂CH₃、–CH(CH₃)CH–CHCH、–CH(CH₃)CH₂CH–CH₂、–CH₂CH–C(CH₃)₂1-cyclopent-1-enyl, 1-cyclopent-2-enyl, 1-cyclopent-3-enyl, 1-cyclohex-1-enyl, 1-cyclohex-2-enyl and 1-cyclohex-3-enyl.

As used herein, "alkylaryl" refers to alkyl-substituted aryl groups, and "substituted alkylaryl" refers to alkylaryl groups further bearing one or more substituents described above. Furthermore, "aralkyl" as used herein refers to an alkyl group substituted with an aryl group as defined above.

As used herein, the term "hetero" refers to a group or moiety containing one or more heteroatoms, such as N, O, Si and S. Thus, for example, "heterocyclic" refers to a cyclic group having, for example, N, O, Si or S as part of a ring structure. The "heteroalkyl," "heterocycloalkyl," and "heteroaryl" moieties are alkyl, cycloalkyl, and aryl, respectively, as defined above containing N, O, Si or S as part of their structure.

As used herein, the term "equivalent weight" refers to the molecular weight divided by the number of functional groups of interest. Thus, "epoxy equivalent weight" (EEW) refers to the weight in grams of a resin containing one equivalent of epoxy groups.

As used herein, the term "epoxide" refers to a compound characterized by the presence of at least one cyclic ether group, i.e., a compound in which an ether oxygen atom is attached to two adjacent carbon atoms to form a cyclic structure. The term is intended to include monoepoxy compounds, polyepoxy compounds (having two or more epoxy groups), and epoxide-terminated prepolymers. The term "monoepoxy compound" is intended to mean an epoxy compound having one epoxy group. The term "polyepoxide" is intended to mean an epoxy compound having at least two epoxy groups. The term "diepoxy compound" is intended to mean an epoxy compound having two epoxy groups.

Epoxides may be unsubstituted, but may also be inertly substituted. Exemplary inert substituents include chloro, bromo, fluoro, and phenyl.

The molecular weights referred to in this specification may be measured by Gel Permeation Chromatography (GPC) using polystyrene calibration standards, for example, according to ASTM 3536.

Unless otherwise specified, the viscosity of the compositions described herein is measured using an Anton Paar viscometer (model MCR 301) at standard conditions of 25 ℃ and 50% Relative Humidity (RH). The viscometer is calibrated once a year and checked by the service department. Calibration was performed using specialty oils of known viscosity (which varied between 5,000cps and 50,000 cps) (parallel plate PP25, and at a shear rate of 11/s, 23 ℃). The measurements of the compositions according to the invention were carried out using a parallel plate PP20 at different shear rates ranging from 1.51/s to 1001/s.

Detailed Description

First part of a two-part (2K) composition

The first part of the two-part (2K) composition comprises: (meth) acrylate ester monomers; a copolymerizable acid; and an electrolyte.

(meth) acrylate ester monomer

The first part of the composition comprises (meth) acrylate monomers, which are typically present in an amount of 20 to 80 wt%, based on the weight of the first part: it is preferred that the (meth) acrylate monomer comprises from 40 to 75 wt%, for example from 47 to 68 wt% or from 53 to 60 wt% of the first part.

These (meth) acrylate monomer amounts are preferable because an amount of more than 80% may adversely affect the initial adhesion properties and the debonding effect, while a small amount (mainly less than 20%) may cause a decrease in the initial adhesion properties.

There is no particular intention to limit the use of (meth) acrylates herein and it is believed that the (meth) acrylate monomer may be any ester of acrylic or methacrylic acid known in the art. That is, exemplary (meth) acrylic monomers include, but are not limited to:

c of (meth) acrylic acid₁-C₁₈Alkyl esters such as methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, butyl (meth) acrylate (all isomers), hexyl (meth) acrylate, n-heptyl (meth) acrylate, n-octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-nonyl (meth) acrylate, n-decyl (meth) acrylate, n-dodecyl (meth) acrylate, and n-octadecyl (meth) acrylate;

c of (meth) acrylic acid₃-C₁₈Cyclic alkyl esters such as cyclohexyl (meth) acrylate and isobornyl (meth) acrylate;

c of (meth) acrylic acid₆-C₁₈Aryl esters such as phenyl (meth) acrylate and tolyl (meth) acrylate;

c of (meth) acrylic acid₇-C₂₄Aralkyl esters such as benzyl (meth) acrylate;

c of (meth) acrylic acid₁-C₁₈Alkoxyalkyl esters, e.g. 2-methoxyethyl (meth) acrylate, 2-ethoxyethyl (meth) acrylate and (meth) acrylic acid) 3-methoxybutyl acrylate;

fluorine-containing C of (meth) acrylic acid₁-C₁₈Alkyl esters such as trifluoromethyl (meth) acrylate, 2-trifluoromethyl ethyl (meth) acrylate, 2-perfluoroethyl-2-perfluorobutyl ethyl (meth) acrylate, 2-perfluoroethyl (meth) acrylate, perfluoromethyl (meth) acrylate, diperfluoromethylmethyl (meth) acrylate, 2-perfluoromethyl-2-perfluoroethylmethyl (meth) acrylate, 2-perfluorohexylethyl (meth) acrylate, 2-perfluorodecylethyl (meth) acrylate and 2-perfluorohexadecylethyl (meth) acrylate;

c of (meth) acrylic acid₁-C₁₈Hydroxyalkyl esters such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate and pentaerythritol tri (meth) acrylate;

di/polyesters of di/polyfunctional alcohols, for example ethylene glycol di (meth) acrylate, 1, 3-or 1, 4-butanediol di (meth) acrylate, 1, 6-hexanediol di (meth) acrylate and trimethylolpropane tri (meth) acrylate;

c of (meth) acrylic acid₁-C₁₈Aminoalkyl esters, such as 2-aminoethyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, and (meth) acryloyloxyethoxyethoxyethoxyethylethylamine;

of (meth) acrylic acid containing C₁-C₁₈Alkyl esters of alkoxysilyl groups, such as gamma- (methacryloxypropyl) trimethoxysilane;

an ethylene oxide or propylene oxide adduct of (meth) acrylic acid; and

(meth) acrylates formed from alcohols carrying other functional groups, for example tetrahydrofurfuryl (meth) acrylate.

For the sake of completeness, it is not excluded that the first part of the composition comprises a macromonomer component consisting of one or more oligomers selected from the group consisting of urethane (meth) acrylates, polyester (meth) acrylates and polyether (meth) acrylates. However, such oligomeric compounds may be monofunctional or multifunctional with respect to polymerizable (meth) acrylate functionality, but should generally not constitute more than 30% by weight of the total (meth) acrylate monomers in the first portion, based on repeating structural urethane, ester and ether subunits.

As known in the art, urethane (meth) acrylate oligomers can be prepared by the reaction of a multifunctional (meth) acrylate bearing hydroxyl groups with a polyisocyanate as defined above. In particular, the multifunctional (meth) acrylate bearing hydroxyl groups may be chosen from: 2-hydroxyethyl (meth) acrylate, 2-hydroxyisopropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, hydroxyethyl caprolactone (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, and combinations thereof.

Suitable polyester (meth) acrylate oligomers are obtained by reacting (meth) acrylic acid with a polyester prepared from a polybasic acid or anhydride thereof and a polyhydric alcohol. Examples of polyacids include, but are not limited to: phthalic acid, succinic acid, adipic acid, glutaric acid, sebacic acid, isosebacic acid, tetrahydrophthalic acid, hexahydrophthalic acid, dimer acid, trimellitic acid, pyromellitic acid, pimelic acid, and azelaic acid. Examples of polyols include, but are not limited to: 1, 6-hexanediol, diethylene glycol, 1, 2-propanediol, 1, 3-butanediol, neopentyl glycol, dipropylene glycol, polyethylene glycol and polypropylene glycol.

As is known in the art, polyether (meth) acrylate oligomers may be obtained by a transesterification reaction between a polyether and a (meth) acrylate, such as ethyl methacrylate. Exemplary polyethers include those obtained from ethoxylated or propoxylated trimethylolpropane, pentaerythritol, and the like, or by the polyetherylation of 1, 4-propanediol and the like.

In a preferred embodiment, the first part comprises at least one (meth) acrylate monomer selected from the group consisting of: methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, t-butyl (meth) acrylate, n-pentyl (meth) acrylate, n-hexyl (meth) acrylate, cyclohexyl (meth) acrylate, n-heptyl (meth) acrylate, n-octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, nonyl (meth) acrylate, decyl (meth) acrylate, dodecyl (meth) acrylate, phenyl (meth) acrylate, tolyl (meth) acrylate, benzyl (meth) acrylate, 2-methoxyethyl (meth) acrylate, 3-methoxybutyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, t-butyl (meth) acrylate, n-pentyl (meth) acrylate, n-hexyl (meth) acrylate, cyclohexyl (meth) acrylate, n-heptyl (meth) acrylate, n-octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, n-butyl (meth) acrylate, n-butyl acrylate, n, Octadecyl (meth) acrylate, glycidyl (meth) acrylate, isobornyl (meth) acrylate, 2-aminoethyl (meth) acrylate, y- (meth) acryloyloxypropyltrimethoxysilane, ethylene oxide- (meth) acrylate adduct, trifluoromethyl (meth) acrylate, 2-trifluoromethylethyl (meth) acrylate, 2-perfluoroethylethyl (meth) acrylate, 2-perfluoroethyl-2-perfluorobutylethyl (meth) acrylate, 2-perfluoroethyl (meth) acrylate, perfluoromethyl (meth) acrylate, diperfluoromethylmethyl (meth) acrylate, 2-perfluoromethyl-2-perfluoroethylmethyl (meth) acrylate, 2-perfluorohexylethyl (meth) acrylate, 2-perfluorodecylethyl (meth) acrylate, 2-perfluorohexadecylethyl (meth) acrylate, isobornyl (meth) acrylate, 2-aminoethylmethacrylate, y-loxyethyl (meth) acrylate, and mixtures thereof, Ethoxylated trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, dipentaerythritol monohydroxypentaacrylate, pentaerythritol triacrylate, ethoxylated trimethylolpropane triacrylate, 1, 6-hexanediol diacrylate, neopentyl glycol diacrylate, pentaerythritol tetraacrylate, 1, 2-butanediol diacrylate, ethoxylated trimethylolpropane tri (meth) acrylate, propoxylated glycerol tri (meth) acrylate, trimethylolpropane tri (meth) acrylate, dipentaerythritol monohydroxypenta (meth) acrylate, tripropylene glycol di (meth) acrylate, propoxylated neopentyl glycol di (meth) acrylate, 1, 4-butanediol di (meth) acrylate, triethylene glycol di (meth) acrylate, butanediol di (meth) acrylate, and ethoxylated bisphenol a di (meth) acrylate.

Good results were obtained in the case where the first part comprises at least one (meth) acrylate monomer selected from the group consisting of methyl (meth) acrylate, ethyl (meth) acrylate, isobornyl (meth) acrylate, ethoxylated trimethylolpropane triacrylate and trimethylolpropane triacrylate, and mixtures thereof.

The (meth) acrylate monomers listed above are preferred because it is believed that the size of the monomers results in the formation of a desirable polymer network, which increases ion transport.

Copolymerizable acids

As noted above, the first part of the composition comprises a copolymerizable acid, which should generally be used in an amount of from 0.25 to 20% by weight based on the weight of the first part: the copolymerizable acid may preferably constitute 6 to 16% by weight, e.g. 10 to 13% by weight, of said first part. For the sake of completeness, although such monomers should generally be used in the form of the free acids, it is not excluded that the constituent acid groups of the monomers are partially or completely neutralized with a suitable base, provided that this does not affect their participation in the copolymerization.

These copolymerizable acid amounts are preferred because amounts greater than 20% may lead to corrosion problems and gas evolution, while small amounts may lead to incomplete cure and thus reduced initial adhesion properties.

Without intending to limit the present invention, the copolymerizable acid monomer should be selected from: an ethylenically unsaturated carboxylic acid; an ethylenically unsaturated sulfonic acid; and, vinyl phosphonic acid. Suitable ethylenically unsaturated sulfonic acids are, for example, vinylsulfonic acid, styrenesulfonic acid and acrylamidomethylpropanesulfonic acid.

Preferably, the copolymerizable acid of this moiety comprises or consists of an ethylenically unsaturated carboxylic acid selected from the group consisting of: c of alpha, beta-monoethylenically unsaturated monocarboxylic acids, alpha, beta-monoethylenically unsaturated dicarboxylic acids₁-C₆Alkyl half esters, alpha, beta-monoethylenically unsaturated tricarboxylic acids, and C of alpha, beta-monoethylenically unsaturated tricarboxylic acids having at least one free carboxylic acid group₁-C₆An alkyl ester, a carboxylic acid,and mixtures thereof. In particular, the copolymerizable acid of this part comprises or consists of at least one acid selected from methacrylic acid, acrylic acid, itaconic acid, maleic acid, aconitic acid, crotonic acid and fumaric acid.

Applicants have found that a copolymerizable acid will increase the cure speed and metal adhesion of the composition.

Note that the present invention does not exclude the presence of a vinyl monomer copolymerizable with the (meth) acrylate monomer and selected from: styrene monomers such as styrene, vinyltoluene, alpha-methylstyrene and chlorostyrene; fluorine-containing vinyl monomers such as perfluoroethylene, perfluoropropylene and fluorinated vinylidene; silicon-containing vinyl monomers such as vinyltrimethoxysilane and vinyltriethoxysilane; maleimide monomers such as maleimide, methylmaleimide, ethylmaleimide, propylmaleimide, butylmaleimide, hexylmaleimide, octylmaleimide, dodecylmaleimide, octadecylmaleimide, phenylmaleimide, and cyclohexylmaleimide; nitrile group-containing vinyl monomers such as acrylonitrile and methacrylonitrile; amide group-containing vinyl monomers such as acrylamide and methacrylamide; vinyl esters such as vinyl acetate, vinyl propionate, vinyl pivalate, vinyl benzoate, and vinyl cinnamate; olefins such as ethylene and propylene; conjugated dienes such as butadiene and isoprene; and vinyl chloride, vinylidene chloride, allyl chloride and allyl alcohol. However, when included, such vinyl comonomers should constitute less than 40 weight percent, preferably less than 20 weight percent, or less than 10 weight percent, based on the total weight of the copolymerizable acid monomers.

Electrolyte

The first part of the composition comprises from 2.5 to 25 wt% electrolyte based on the weight of the first part: the electrolyte may preferably comprise from 4 to 23 wt%, for example from 5 to 20 wt% of the first part.

These amounts are preferred because an electrolyte amount of more than 25% may result in good debonding effect, but curing may be incomplete and thus may adversely affect the initial adhesive properties, while a small amount may result in lack of debonding effect.

The electrolyte preferably comprises at least one salt having a structural formula selected from the group consisting of:

wherein: r is¹、R²、R³、R⁴、R⁵And R⁶Independently selected from hydrogen, C₁-C₁₈Alkyl radical, C₃-C₁₈Cycloalkyl, C₆-C₁₈Aryl radical, C₇-C₂₄Aralkyl, C₂-C₂₀Alkenyl, -C (O) R^q-C (O) OH, -CN and-NO₂(ii) a And, R^qIs C₁-C₆An alkyl group.

For completeness, the term C₁-C₁₈Alkyl radical, C₃-C₁₈Cycloalkyl, C₆-C₁₈Aryl radical, C₇-C₂₄Aralkyl radical, C₂-C₂₀Alkenyl explicitly includes groups in which one or more hydrogen atoms are replaced by halogen atoms (e.g. C)₁-C₁₈Haloalkyl) or a group substituted by hydroxy (e.g. C)₁-C₁₈Hydroxyalkyl). In particular, it is preferred that R¹、R²、R³、R⁴、R⁵And R⁶Independently selected from hydrogen, C₁-C₁₂Alkyl radical, C₁-C₁₂Haloalkyl, C₁-C₁₂Hydroxyalkyl and C₃-C₁₂A cycloalkyl group. For example, R¹、R²、R³、R⁴、R⁵And R⁶Can be independently selected from hydrogen and C₁-C₆Alkyl radical, C₁-C₆Alkyl halidesRadical and C₁-C₆A hydroxyalkyl group.

There is no particular intention to limit the counter anion (X) that may be used in the electrolyte^–). Exemplary anions may be selected from:

a halide;

PF of the formula₆ ^-、CF₃SO₃ ^-、(CF₃SO₃)₂N^-、CF₃CO₂ ^-And CCl₃CO₂ ^-The pseudohalide of (a) and the halogen-containing compound,

·CN^-、SCN^-and OCN^-；

A phenate salt;

general formula SO₄ ^2-、HSO₄ ^-、SO₃ ^2-、HSO₃ ^-、R^aOSO₃ ^-And R^aSO₃ ^-Sulfates, sulfites and sulfonates of (a);

general formula PO₄ ^3-、HPO₄ ^2-、H₂PO₄ ^-、R^aPO₄ ^2-、HR^aPO₄ ^-And R^aR^bPO₄ ^-A phosphate of (a);

general formula R^aHPO₃ ^-、R^aR^bPO₂ ^-And R^aR^bPO₃ ^-Phosphonates (Phosphonates) and phosphinates (Phosphonates);

general formula (xxxvii): PO₃ ^3-、HPO₃ ^2-、H₂PO₃ ^-、R^aPO₃ ^2-、R^aHPO₃ ^–And R^aR^bPO₃ ^-Phosphites (Phosphites);

general formula R^aR^bPO₂ ^-、R^aHPO₂ ^-、R^aR^bPO^-And R^aHPO^-Hypophosphites (phosphinites) and phosphinates (phosphinites);

general formula R^aCOO^-The carboxylic acid anion of (a);

hydroxycarboxylate and saccharate anions;

saccharinate (salt of sulfonimide phthalate);

general formula BO₃ ^3-、HBO₃ ^2-、H₂BO₃ ^-、R^aR^bBO₃ ^-、R^aHBO₃ ^-、R^aBO₃ ^2-、B(OR^a)(OR^b)(OR^c)(OR^d)^-、B(HSO₄)^-And B (R)^aSO₄)^-The borate of (1);

general formula R^aBO₂ ^2-And R^aR^bBO^-The borate of (1);

general formula HCO₃ ^-、CO₃ ^2-And R^aCO₃ ^-Carbonates and carbonic acid esters of (a);

SiO of the general formula₄ ^4-、HSiO₄ ^3-、H₂SiO₄ ^2-、H₃SiO₄ ^-、R^aSiO₄ ^3-、R^aR^bSiO₄ ^2-、R^aR^bR^cSiO₄ ^-、HR^aSiO₄ ^2-、H₂R^aSiO₄ ^–And HR^aR^bSiO₄ ^-Silicates and silicates of (a);

general formula R^aSiO₃ ^3-、R^aR^bSiO₂ ^2-、R^aR^bR^cSiO^-、R^aR^bR^cSiO₃ ^-、R^aR^bR^cSiO₂ ^–And R^aR^bSiO₃ ^2-Alkyl of (2)Aryl and aryl silanolates;

pyridine and pyrimidine salts;

carboxylic acid imides, bis (sulfonyl) imides and sulfonyl imides of the general formula:

methylated compounds of the general formula:

general formula R^aO^-Alkoxides and aryloxides of (a); and

general formula S^2-、HS^-、[S_v]^2-、[HS_v]^-And [ R ]^aS]^-Sulfides, hydrogen sulfides, polysulfides, hydrogen polysulfides and thiolates of (A)

In the general formula

v is an integer from 2 to 10.

R^a、R^b、R^cAnd R^dIndependently selected from hydrogen, C₁-C₁₂Alkyl radical, C₅-C₁₂Cycloalkyl radical, C₅-C₁₂Heterocycloalkyl radical, C₆-C₁₈Aryl and C₅-C₁₈A heteroaryl group.

Based on the definitions in the above list, preferred anions are selected from: a halide; pseudohalides and halogen-containing compounds as defined above; carboxylic acid anions, in particular formate, acetate, propionate, butyrate and lactate; hydroxy carboxylic acid anion; pyridine salts and pyrimidine salts; carboxylic acid imides, bis (sulfonyl) imides, and sulfonyl imides; sulfates, especially methyl sulfate and ethyl sulfate; a sulfite; sulfonates, especially methanesulfonate; and phosphates, in particular dimethyl phosphate, diethyl phosphate and (2-ethylhexyl) phosphate.

The electrolyte of the first part is preferably selected from the group consisting of 1-ethyl-3-methylimidazolium methanesulfonate, 1-ethyl-3-methylimidazolium methylsulfate, 1-hexyl-3-methylimidazolium 2- (2-fluoroanilino) -pyridinium, 1-hexyl-3-methylimidazolium imide, 1-butyl-1-methyl-pyrrolidinium 2- (2-fluoroanilino) -pyridinium, 1-butyl-1-methyl-pyrrolidinium imide, trihexyl (tetradecyl) phosphonium 2- (2-fluoroanilino) -pyridinium, cyclohexyltrimethylammonium bis (trifluoromethylsulfonyl) imide, bis (2-hydroxyethyl) ammonium trifluoroacetate, N-dimethyl (2-hydroxyethyl) ammonium octanoate, methyltrioctylammonium bis (trifluoromethylsulfonyl) imide, N-ethyl-N-N-N-tetramethylguanidine trifluoromethanesulfonate, N-ethyl-N-N-N-tetramethylguanidine, N-methyl-pyrrolidinium methanesulfonate, 1-ethyl-3-methylimidazolium methylsulfate, 1-butyl-1-methyl-pyrrolidinium 2- (2-fluoroanilino) -pyridinium, trihexyl) trimethylammonium, trihexyl-2- (2-trifluoromethylsulfonyl) imidazolium) imide, cyclohexylammonium, and N-bis (trifluoromethylsulfonyl) imide, Guanidine trifluoromethanesulfonate, 1-butyl-4-methylpyridinium bromide, 1-butyl-3-methylpyridinium tetrafluoroborate, 1-butyl-3-hydroxymethylpyridinium ethyl sulfate, 1-butyl-1-methylpyrrolidinium bis (trifluoromethylsulfonyl) imide, 1-butyl-methylpyrrolidinium tris (pentafluoroethyl) trifluorophosphate, 3-methylimidazolium ethyl sulfate, 1-ethyl-3-methylimidazolium chloride, 1-ethyl-3-ethyl-methylimidazolium bromide, 1-butyl-3-methylimidazolium chloride, 1-hexyl-3-methylimidazolium chloride, 1-octyl-3-methylimidazolium chloride, 1-methyl-3-octylimidazolium chloride, 1-propyl-3-methylimidazolium iodide, 1-butyl-3-methylimidazolium tetrafluoroborate, 1-butyl-3-methylimidazolium triflate, 1-butyl-3-methylimidazolium hexafluorophosphate, 1-butyl-2, 3-dimethylimidazolium tetrafluoroborate, 1-butyl-2, 3-dimethylimidazolium hexafluorophosphate, 1-butylimidazole, 1-methylimidazolium tetrafluoroborate, tetrabutylphosphonium tris (pentafluoroethyl) trifluorophosphate, trihexyl (tetradecyl) phosphonium tetrafluoroborate and mixtures thereof. Particularly preferably used is at least one of 1-ethyl-3-methylimidazolium methanesulfonate and 1-ethyl-3-methylimidazolium methylsulfate.

Second part of two-part (2K) composition

The second part of the two-part composition comprises: a first curing agent; a second curing agent; and a solubilizer.

First curing agent

As mentioned above, the second part of the composition comprises a first curing agent, which should generally be used in an amount of 25 to 75 wt%, based on the weight of the second part: the first curing agent may preferably comprise 50 to 75 wt% of the second part, for example 55 to 70 wt% or 60 to 70 wt% or 61 to 65 wt%; alternatively, the first curing agent may preferably constitute 25 to 60 wt%, such as 30 to 55 wt% or 30 to 45 wt%.

These first curing agent amounts are preferred because amounts greater than 75% may result in excess first curing agent and unwanted reactions may adversely affect the properties of the composition, while small amounts (mainly below 25%) may result in incomplete curing and thus poor initial adhesive performance.

In an important embodiment, the first curing agent comprises or consists of at least one radical initiator which decomposes under the action of heat to provide free radicals. Exemplary thermally activated free radical initiators include: peroxides, including ketone peroxides; a hydroperoxide; a peroxycarbonate salt; peracetic acid; azo compounds, such as 2,2 '-Azobisisobutyronitrile (AIBN) or 2,2' -azobis (2, 4-dimethylvaleronitrile), 4 '-azobis (4-cyanovaleric acid) or 1,1' -azobis (cyclohexanecarbonitrile); tetrazine; and persulfate compounds, such as potassium persulfate. Free radical initiators which are solid at room temperature are preferred. Alternatively, or in addition to this preferred statement, it is desirable that the free radical initiator has a half-life of at least 10 hours at a temperature of 60 ℃.

While certain peroxides, such as dialkyl and diaryl peroxides, have been disclosed as useful curatives, and are actually useful herein, in, inter alia, U.S. patent No. 3,419,512(Lees) and U.S. patent No. 3,479,246(Stapleton), hydroperoxides also represent an important class of curatives for use in the present invention. In this connection, although hydrogen peroxide itself may be used, it is preferred to use an organic hydroperoxide. For the sake of completeness, the definition of hydroperoxide includes substances such as organic peroxides or organic peresters which decompose or hydrolyze to form organic hydroperoxides in situ: examples of such peroxides and peresters are cyclohexyl peroxide and hydroxycyclohexyl peroxide and tert-butyl perbenzoate, respectively.

Without intending to limit the invention, representative hydroperoxide compounds have the general formula:

R^pOOH

wherein: r^pIs a hydrocarbyl group containing up to 18 carbon atoms, and preferably wherein: r^pIs C₁-C₁₂Alkyl radical, C₆-C₁₈Aryl or C₇-C₁₈An aralkyl group.

As exemplary compounds that may be used alone or in combination as the first curing agent, there may be mentioned: cumene Hydroperoxide (CHP), p-menthane hydroperoxide, tert-butyl hydroperoxide (TBH), tert-butyl perbenzoate, tert-butyl peroxyacetate, tert-amyl hydroperoxide, 1,2,3, 4-tetramethyl butyl hydroperoxide, lauroyl peroxide, benzoyl peroxide (also known as dibenzoyl peroxide, C)₁₄H₁₀O₄CAS number 94-36-0), 1, 3-bis (t-butylperoxyisopropyl) benzene, diacetyl peroxide, butyl 4, 4-bis (t-butylperoxy) valerate, p-chlorobenzoyl peroxide, t-butylcumyl peroxide, di-t-butyl peroxide, dicumyl peroxide, 2, 5-dimethyl-2, 5-di-t-butylperoxyhexane, 2, 5-dimethyl-2, 5-di-t-butyl-peroxy hex-3-yne and 4-methyl-2, 2-di-t-butylperoxypentane.

A second curing agent

As mentioned above, the second part of the composition comprises a second curing agent, which should generally be used in an amount of 0.01 to 5 wt%, based on the weight of the second part: the second curing agent may preferably comprise 0.01 to 1 wt%, for example 0.03 to 1 wt% or 0.05 to 0.3 wt% of the second part.

These second curing amounts are preferred because amounts greater than 5% may adversely affect the debonding effect, while small amounts (mainly less than 0.01%) may result in a decrease in initial adhesion properties.

The second curing agent is included in the composition to increase at least one of the curing speed, adhesive strength, and adhesive quality of the adhesive composition.

In an important embodiment, the second curing agent comprises or consists of at least one compound which is a salt or complex of a transition metal which can be selected from Fe, Co, V, Ti, Mn, Cu, Sn, Cr, Ni, Mo, Ge, Sr, Pd, Pt, Nb, Sb, Re, Os, Ir, Pt, Au, Hg, Te, Rb and Bi, and in particular should be selected from Fe, Co, V, Mn and Cu.

It has proved advantageous if the second agent comprises or consists of at least one iron compound selected from the group consisting of: an iron carboxylate; 1, 3-dioxoiron complex; ammonium-iron-ferrocyanide [ hexa (cyano-C) ferric ferrate (3+) ammonium salt (4-)](ii) a And a dicyclopentadienyl iron complex. In this regard, exemplary iron carboxylates include iron lactate, iron naphthenate, iron 2-ethylhexanoate (iron octanoate), iron formate, iron acetate, iron propionate, iron butyrate, iron valerate, iron hexanoate, iron heptoate, iron nonanoate, iron decanoate, iron neodecanoate, and iron dodecanoate. Exemplary 1, 3-dioxoiron complexes include iron acetylacetonate, and iron complexes of acetylacetone, benzoylacetone, dibenzoylmethane, and acetoacetates (e.g., diethyl acetoacetamide, dimethyl acetoacetamide, dipropyl acetoacetamide, dibutyl acetoacetamide, methyl acetoacetate, ethyl acetoacetate, propyl acetoacetate, and butyl acetoacetate). An example of a dicyclopentadienyl iron complex is a complex comprising iron and two substituted or unsubstituted cyclopentadienyl ligands, wherein the optional substituents on the cyclopentadienyl ring are selected from C₁-C₁₂Alkyl radical, C₆-C₁₈Aryl and C₇-C₁₈An aralkyl group. One specific example of a dicyclopentadienyl iron complex is ferrocene (bis (. eta.5-cyclopentadienyl) iron).

It should be noted that fe (ii) and fe (iii) complexes may be used. Further, it may be mentioned that it is particularly preferable to use ferrocene as at least a part of the second curing agent.

As further exemplary transition metal compounds that may be used in or as the second curing agent, salts and complexes of copper, cobalt, vanadium and manganese may be mentioned in particular. The cobalt compounds can be used here as transition metals and, due to the small amounts used, have no legislative and toxicity problems. Suitable counter anions present in the salt include: a halogen ion; nitrate radical; sulfate radical; a sulfonate group; phosphate radical; a phosphonate group; an oxide; or a carboxylate, such as lactate, 2-ethylhexanoate, acetate, propionate, butyrate, oxalate, laurate, oleate, linoleate, palmitate, stearate, acetylacetonate, octanoate, nonanoate, heptanoate, neodecanoate or naphthenate.

Solubilizer

The second part of the two part (2K) composition must comprise a solubilizer, which is typically present in an amount of 20 to 45 wt% based on the weight of the second part: preferably the solubiliser comprises 28 to 40 wt%, for example 35 to 38 wt% of the second portion. The solubilizer has the function of promoting miscibility of the electrolyte in the adhesive composition formed after mixing of its two parts: the solubilizer may or may not form part of the polymer matrix formed upon curing of the adhesive composition, but does serve to facilitate ion transfer therein. The solubilizer is therefore preferably a polar compound and should ideally be a liquid at room temperature.

These amounts of solubilizing agent are preferred because amounts greater than 45% may adversely affect adhesion and cure performance, while small amounts (primarily less than 20%) may result in the second part of the composition being a solid, thus preventing blending of the first and second parts.

In a first embodiment, the solubilizing agent comprises or consists of one or more liquid epoxy resins. The epoxy resin used herein may include monofunctional epoxy resins, multifunctional or polyfunctional epoxy resins, and combinations thereof. The epoxy resin may be a pure compound, but may equally be a mixture of epoxy-functional compounds, including mixtures of compounds having different numbers of epoxy groups per molecule. The epoxy resin may be saturated or unsaturated, aliphatic, cycloaliphatic, aromatic or heterocyclic, and may be substituted. Furthermore, the epoxy resin may be monomeric or polymeric.

Without intending to limit the invention, exemplary monoepoxy compounds include: an alkylene oxide; epoxy-substituted alicyclic hydrocarbons such as cyclohexene oxide, vinylcyclohexene monoxide, (+) -cis-limonene oxide, (+) -cis, trans-limonene oxide, (-) -cis, trans-limonene oxide, epoxycyclooctane, epoxycyclododecane and α -pinene oxide (α -pinene oxide); an epoxy-substituted aromatic hydrocarbon; monoepoxy-substituted alkyl ethers of monohydric alcohols or phenols, such as glycidyl ethers of aliphatic, cycloaliphatic, and aromatic alcohols; mono-epoxy substituted alkyl esters of monocarboxylic acids, such as glycidyl esters of aliphatic, alicyclic and aromatic monocarboxylic acids; mono-epoxy substituted alkyl esters of polycarboxylic acids in which one or more of the other carboxyl groups are esterified with an alkanol; alkyl and alkenyl esters of epoxy-substituted monocarboxylic acids; alkylene oxide ethers of polyhydric alcohols in which one or more other OH groups are esterified or etherified with a carboxylic acid or alcohol; and monoesters of polyhydric alcohols and epoxy monocarboxylic acids in which one or more other OH groups are esterified or etherified with a carboxylic acid or alcohol.

By way of example, the following glycidyl ethers may be mentioned as monoepoxy compounds suitable for use herein: methyl glycidyl ether, ethyl glycidyl ether, propyl glycidyl ether, butyl glycidyl ether, pentyl glycidyl ether, hexyl glycidyl ether, cyclohexyl glycidyl ether, octyl glycidyl ether, 2-ethylhexyl glycidyl ether, allyl glycidyl ether, benzyl glycidyl ether, phenyl glycidyl ether, 4-tert-butylphenyl glycidyl ether, 1-naphthyl glycidyl ether, 2-chlorophenyl glycidyl ether, 4-bromophenyl glycidyl ether, 2,4, 6-trichlorophenyl glycidyl ether, 2,4, 6-tribromophenyl glycidyl ether, pentafluorophenyl glycidyl ether, o-tolyl glycidyl ether, m-tolyl glycidyl ether, and p-tolyl glycidyl ether.

In certain embodiments, the monoepoxy compound corresponds to the following formula (I) herein:

wherein: r^w、R^x、R^yAnd R^zMay be the same or different and is independently selected from hydrogen, halogen atom, C₁-C₈Alkyl radical, C₃-C₁₀Cycloalkyl radical, C₂-C₁₂Alkenyl radical, C₆-C₁₈Aryl or C₇-C₁₈Aralkyl, with the proviso that R is^yAnd R^zIs not hydrogen.

Preferably, R is^w、R^xAnd R^yIs hydrogen, and R^zIs phenyl or C₁-C₈Alkyl, more preferably C₁-C₄An alkyl group.

With these embodiments in mind, exemplary monoepoxides include: ethylene oxide, 1, 2-propylene oxide (propylene oxide), 1, 2-butylene oxide, cis-2, 3-butylene oxide, trans-2, 3-butylene oxide, 1, 2-pentylene oxide, 1, 2-hexylene oxide, 1, 2-heptylene oxide, decylene oxide, butadiene oxide, isoprene oxide and styrene oxide.

In the present invention, the use of at least one monoepoxy compound selected from the group consisting of: ethylene oxide, propylene oxide, cyclohexene oxide, (+) -cis-limonene oxide, (+) -cis, trans-limonene oxide, (-) -cis, trans-limonene oxide, epoxycyclooctane and epoxycyclododecane.

Also, without intending to limit the invention, suitable polyepoxides may be liquid, solid, or solution in a solvent. Furthermore, such polyepoxides should have an epoxy equivalent weight of from 100 to 700g/eq, for example from 120 to 320 g/eq. And in general, diepoxy compounds having an epoxy equivalent of less than 500g/eq, or even less than 400g/eq are preferred: this is primarily from a cost perspective, since lower molecular weight epoxy resins require more limited purification processing in their production.

As examples of types or groups of polyepoxides which can be polymerized in the present invention, mention may be made of: glycidyl ethers of polyhydric alcohols and polyhydric phenols; glycidyl esters of polycarboxylic acids; and epoxidized polyethylenically unsaturated (ethylenically unsaturated) hydrocarbons, esters, ethers, and amides.

Suitable diglycidyl ether compounds may be aromatic, aliphatic, or cycloaliphatic in nature, and thus may be derived from dihydric phenols and glycols. And useful classes of such diglycidyl ethers are: diglycidyl ethers of aliphatic and cycloaliphatic diols, such as 1, 2-ethanediol, 1, 4-butanediol, 1, 6-hexanediol, 1, 8-octanediol, 1, 12-dodecanediol, cyclopentanediol and cyclohexanediol; diglycidyl ethers based on bisphenol a; bisphenol F diglycidyl ether; polyglycidyl ethers based on polyalkylene glycols, in particular polypropylene glycol diglycidyl ether; and glycidyl ethers based on polycarbonate diols.

Other exemplary polyepoxides include, but are not limited to: glycerol polyglycidyl ether, trimethylolpropane polyglycidyl ether, pentaerythritol polyglycidyl ether, diglycerol polyglycidyl ether, polyglycerol polyglycidyl ether, and sorbitol polyglycidyl ether.

The glycidyl esters of polycarboxylic acids useful in the present invention are derived from polycarboxylic acids containing at least two carboxylic acid groups and no other groups reactive with epoxide groups. The polycarboxylic acids may be aliphatic, cycloaliphatic, aromatic and heterocyclic. Preferred polycarboxylic acids are those containing no more than 18 carbon atoms per carboxylic acid group, suitable examples of which include, but are not limited to: oxalic acid, sebacic acid, adipic acid, succinic acid, pimelic acid, suberic acid, glutaric acid, dimer acids and trimer acids of unsaturated fatty acids, for example dimer acids and trimer acids of linseed fatty acids, phthalic acid, isophthalic acid, terephthalic acid, trimellitic acid, trimesic acid, phenylenediacetic acid, chlorendic acid, hexahydrophthalic acid, in particular hexahydrophthalic acid (1, 2-cyclohexanedicarboxylic acid), biphenyl acids, naphthalenedicarboxylic acid, polyacid-terminated esters of dibasic acids and aliphatic polyols, polymers and copolymers of (meth) acrylic acid and crotonic acid.

Other suitable diepoxides that may also be mentioned include: di-unsaturated fatty acid C₁-C₁₈Diepoxides of alkyl esters, butadiene diepoxides, polybutadiene diglycidyl ether, vinylcyclohexene diepoxides, and limonene diepoxides.

And examples of preferred polyepoxides include: bisphenol A epoxy resins, e.g. DER^TM 331、DER^TM332、DER^TM 383、JER^TM828 and Epotec YD 128; bisphenol F epoxy resins, e.g. DER^TM354; bisphenol A/F epoxy resin blends, e.g. DER^TM353; aliphatic glycidyl ethers, e.g. DER^TM736; polypropylene glycol diglycidyl ethers, e.g. DER^TM732; epoxy novolac resins, e.g. DEN^TM438; brominated epoxy resins, e.g. DER^TM542; castor oil triglycidyl ethers, e.g. ERISYS^TMGE-35H; polyglycerol-3-polyglycidyl ethers, e.g. ERISYS^TMGE-38; and, sorbitol glycidyl ethers, e.g. ERISYS^TMGE-60; and bis (2, 3-epoxypropyl) cyclohexane-1, 2-dicarboxylate available as Lapox Arch-11. It should be noted that a solubilizer comprising or consisting of bisphenol a epoxy resin is particularly preferred.

In the case where the solubiliser of the second part of the composition is based on one or more epoxy resins, the present invention does not exclude that the solubiliser further comprises one or more cyclic compounds selected from: an oxetane; a cyclic carbonate; a cyclic anhydride; and, a lactone. The following citation disclosure may help to disclose suitable cyclic carbonate functional compounds: U.S. patent nos. 3,535,342; U.S. patent nos. 4,835,289; U.S. patent nos. 4,892,954; british patent No. GB-A-1,485,925; and, EP-A-0119840. However, such other cyclic compounds should constitute less than 20 wt-%, preferably less than 10 wt-% or less than 5 wt-%, based on the total weight of the epoxy compound.

In another embodiment, which is not intended to be mutually exclusive with respect to what is given above, the solubilizer of the second fraction comprises at least one polymer which is liquid at room temperature and is selected from: polyphosphazene; polymethylene sulfide; a polyoxyalkylene glycol; and polyethyleneimine. It is possible to note that preference is given to polyoxy (C) having a weight-average molecular weight of from 350 to 10000g/mol, for example from 500 to 5000g/mol₂-C₃) An alkylene glycol.

Additives and auxiliary ingredients

The compositions obtained in the present invention generally further comprise adjuvants and additives which can impart improved properties to these compositions. For example, adjuvants and additives may impart one or more of the following: improved elastic properties; improved elastic recovery; longer allowed processing times; faster curing times; and lower residual tack. Such adjuvants and additives may be included independently of each other in either a single part or in two parts of a two (2K) part composition, including: plasticizers, stabilizers, including uv stabilizers, antioxidants, toughening agents, conductive fillers, non-conductive fillers, reactive diluents, drying agents, adhesion promoters, bactericides, flame retardants, rheological adjuvants, colored pigments or dye pastes, and/or optionally also small amounts of non-reactive diluents.

Such adjuvants and additives may be used in such combinations and proportions as are desired, so long as they do not adversely affect the properties and basic performance of the composition. Although exceptions may be present in some cases, these adjuvants and additives should not amount to more than 50% by weight of the total composition, preferably not more than 20% by weight of the composition.

For the sake of completeness, it is noted that auxiliary materials and additives containing reactive groups are generally blended into the appropriate parts of the two (2K) part composition to ensure its storage stability. The non-reactive material may be formulated in one or both of the two parts.

"plasticizers" for the purposes of the present invention are substances which reduce the viscosity of the composition and thus promote its processability. Plasticizers herein may comprise up to10% or up to 5% by weight, and preferably selected from: polydimethylsiloxane (PDMS); a diurethane; monofunctional, linear or branched C₄-C₁₆Ethers of alcohols, such as Cetiol OE (available from CognisDeutschland GmbH, Dusseldorf); abietate, butyrate, thiobutyrate, acetate, propionate, and citrate; esters based on nitrocellulose and polyvinyl acetate; a fatty acid ester; a dicarboxylic acid ester; esters of OH-group-bearing or epoxidized fatty acids; glycolic acid esters; benzoic acid esters; a phosphate ester; a sulfonate ester; trimellitic acid ester; an epoxidized plasticizer; polyether plasticizers, such as capped polyethylene glycols or polypropylene glycols; polystyrene; a hydrocarbon plasticizer; chlorinated paraffin; and mixtures thereof. Note that in principle, phthalates can be used as plasticizers, but these are not preferred due to their toxicological potential. Preferably, the plasticizer comprises or consists of one or more Polydimethylsiloxanes (PDMS).

"stabilizers" for the purposes of the present invention are to be understood as meaning antioxidants, UV stabilizers or hydrolysis stabilizers. In this context, the stabilizer may constitute up to 10% by weight or up to 5% by weight of the total composition, based on the total weight of the composition. Standard commercial examples of stabilizers suitable for use herein include: a sterically hindered phenol; a thioether; benzotriazole; a benzophenone; benzoic acid esters; a cyanoacrylate; an acrylate; hindered Amine Light Stabilizer (HALS) type amines; phosphorus; sulfur; and mixtures thereof.

Those compositions of the present invention may optionally comprise toughening rubber dispersed in the form of core-shell particles in an epoxy matrix. The term "core shell rubber" or CSR is used according to its standard meaning in the art to denote a rubber particle core formed of a polymer comprising an elastomer or a rubbery polymer as a main component and a shell layer formed of a polymer graft-polymerized onto the core. The shell layer partially or completely covers the surface of the rubber particle core during graft polymerization. The core should comprise at least 50% by weight of the core shell rubber particles.

The polymeric material of the core should have a glass transition temperature (T) of not more than 0 ℃_g) Preferably-20 ℃ or lowerMore preferably-40 ℃ or less, even more preferably-60 ℃ or less_g). The polymer of the shell is the glass transition temperature (T)_g) Non-elastomeric, thermoplastic or thermosetting polymers above room temperature, preferably above 30 ℃, more preferably above 50 ℃.

Without intending to limit the invention, the core may consist of: homopolymers of dienes, such as homopolymers of butadiene or isoprene; diene copolymers, such as copolymers of butadiene or isoprene with one or more ethylenically unsaturated monomers (e.g. vinyl aromatic monomers, (meth) acrylonitrile or (meth) acrylates); polymers based on (meth) acrylate monomers, such as polybutyl acrylate; and silicone elastomers such as polydimethylsiloxane and cross-linked polydimethylsiloxane.

Similarly, without intending to limit the invention, the shell may be composed of a polymer or copolymer of one or more monomers selected from the group consisting of: (meth) acrylates such as methyl methacrylate; vinyl aromatic monomers such as styrene; vinyl cyanides such as acrylonitrile; unsaturated acids and anhydrides such as acrylic acid; and (meth) acrylamide. The polymer or copolymer used in the shell may have acid groups which are ionically crosslinked by the formation of metal carboxylate salts, in particular by the formation of salts of divalent metal cations. The shell polymer or copolymer may also be covalently crosslinked by monomers having two or more double bonds per molecule.

Preferably, any core shell rubber particles included have an average particle diameter (d50) of 10nm to 300nm, for example 50nm to 250 nm: the particle size refers to the diameter or largest dimension of the particles in the particle distribution and is measured by dynamic light scattering. For the sake of completeness, the present application does not preclude the presence of two or more types of Core Shell Rubber (CSR) particles having different particle size distributions in the composition to provide a balance of key properties of the resulting cured product, including shear strength, peel strength, and resin fracture toughness.

The core shell rubber may be selected from commercially available products, examples of which include: paraloid EXL 2650A, EXL 2655 and EXL 2691A from The Dow Chemical Company；

XT100, available from Arkema inc; kane available from Kaneka Corporation

The MX series, in particular MX 120, MX 125, MX 130, MX 136, MX 551, MX 553; also, METABLEN SX-006 is available from Mitsubishi Rayon.

The core shell rubber particles should be included in the composition in total in an amount of 0 to 15 weight percent, for example, up to 10 weight percent, based on the total weight of the composition.

As indicated, the composition according to the invention may additionally comprise a conductive filler. In general, there is no particular intention to limit the shape of the particles used as conductive filler: acicular, spherical, ellipsoidal, cylindrical, beaded, cubic or flaky particles may be used alone or in combination. Furthermore, it is contemplated that agglomerates of more than one particle type may be used. Also, there is no particular intention to limit the size of the particles used as the conductive filler. However, such conductive fillers typically have an average volume particle size as measured by laser diffraction/scattering methods of 1 to 500 μm, for example 1 to 200 μm.

Exemplary conductive fillers include, but are not limited to: silver, copper, gold, palladium, platinum, nickel, gold or silver coated nickel, carbon black, carbon fiber, graphite, aluminum, indium tin oxide, silver coated copper, silver coated aluminum, metal coated glass spheres, metal coated fillers, metal coated polymers, silver coated fibers, silver coated spheres, antimony doped tin oxide, conductive nanospheres, nanosilver, nanoaluminum, nanocopper, nanonickel, carbon nanotubes, and mixtures thereof. Preferably, particulate silver and/or carbon black is used as the conductive filler.

In certain important embodiments, the electrically conductive filler should be included in the composition in an amount of 0 to 10 weight percent, such as up to 5 weight percent, based on the total weight of the composition.

The presence of non-conductive fillers in the composition is not excluded: in addition to moderating the viscosity of the composition, such fillers may be added as needed to lower the coefficient of thermal expansion of the adhesive. In general, there is no particular intention to limit the shape of the particles used as non-conductive filler: acicular, spherical, ellipsoidal, cylindrical, beaded, cubic or platelet-shaped particles may be used alone or in combination. Furthermore, it is contemplated that more than one particle type of agglomerates may be used. Also, there is no particular intention to limit the size of the particles used as the non-conductive filler. However, such non-conductive fillers typically have an average volume particle size as measured by laser diffraction/scattering methods of 0.1 to 1500 μm, for example 1 to 1000 μm or 1 to 500 μm.

Exemplary non-conductive fillers include, but are not limited to, chalk, lime powder, precipitated and/or fumed silicic acid, zeolites, bentonite, magnesium carbonate, diatomaceous earth, alumina, clays, talc, sand, quartz, flint, mica, glass powder, and other ground minerals. Short fibers, such as glass fibers, glass filaments, polyacrylonitrile, carbon fibers or polyethylene fibers, may also be added.

The pyrogenic and/or precipitated silicic acid advantageously has a particle size of from 10 to 90m²BET surface area in g. When they are used, they do not cause any additional increase in the viscosity of the composition according to the invention, but do contribute to the strengthening of the cured composition.

It is likewise conceivable to use compounds having a higher BET surface area, advantageously from 100 to 250m²As filler, pyrogenic and/or precipitated silicic acid in g: because of the larger BET surface area, the effect of reinforcing the cured composition is achieved with a smaller weight proportion of silicic acid.

Also suitable as non-conductive fillers are hollow spheres with a mineral or plastic shell. For example, these may be hollow Glass spheres, which may be sold under the trade name Glass

Are commercially available. Hollow balls based on plastic may be used, for example

Or

And it is described in EP 0520426B 1: they consist of inorganic or organic substances and each have a diameter of 1mm or less, preferably 500 μm or less, preferably between 100 μm and 200 μm.

Non-conductive fillers that impart thixotropy to the composition may be preferred for many applications: such fillers are also described as rheological adjuvants, such as hydrogenated castor oil, fatty acid amides or expandable plastics such as PVC.

The total amount of fillers (conductive and non-conductive) present in the composition of the present invention is preferably from 0 to 20 wt.%, more preferably from 0 to 10 wt.%, based on the total weight of the composition. The desired viscosity of the curable composition is generally determined by the total amount of filler added and it is believed that in order to be easily extrudable from a suitable dispensing device such as a tube, the curable composition should have a viscosity of 3000 to 150,000mPas, preferably 40,000 to 80,000mPas, or even 50,000 to 60,000 mPas.

In order to even further increase the shelf life, it is generally recommended to further stabilize the compositions of the invention with respect to moisture penetration by using a drying agent. It is also sometimes desirable to reduce the viscosity of the adhesive composition according to the invention for a particular application by using one or more reactive diluents. The total amount of reactive diluent present is typically from 0 to 15 wt%, for example from 0 to 5 wt%, based on the total weight of the composition.

The presence of solvents and non-reactive diluents in the compositions of the invention is not excluded insofar as its viscosity can be effectively adjusted. For example, but for illustration only, the composition may comprise one or more of: xylene, 2-methoxyethanol, dimethoxyethanol, 2-ethoxyethanol, 2-propoxyethanol, 2-isopropoxyethanol, 2-butoxyethanol, 2-phenoxyethanol, 2-benzyloxyethanol, benzyl alcohol, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol dibutyl ether, ethylene glycol diphenyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol mono-n-butyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol di-n-butyl ether, propylene glycol phenyl ether, dipropylene glycol phenyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol mono-n-butyl ether, diethylene glycol di-n-butyl ether, propylene glycol phenyl ether, propylene glycol butyl ether, propylene glycol methyl ether, propylene glycol butyl ether, propyleneDipropylene glycol monomethyl ether, dipropylene glycol dimethyl ether, dipropylene glycol di-N-butyl ether, N-methylpyrrolidone, diphenylmethane, diisopropylnaphthalene, petroleum fractions, e.g. petroleum fractions

Products (available from Exxon), alkylphenols, such as tert-butylphenol, nonylphenol, dodecylphenol and 8,11, 14-pentadecenylphenol, styrenated phenols, bisphenols, aromatic hydrocarbon resins, especially those containing phenolic groups, such as ethoxylated or propoxylated phenols, adipates, sebacates, phthalates, benzoates, organophosphates or sulfonates and sulfonamides.

In addition to the above, it is preferred that the non-reactive diluents constitute less than 10 wt.%, in particular less than 5 wt.% or less than 2 wt.%, in total, based on the total weight of the composition.

Exemplary embodiments of two-part (2K) compositions

In one exemplary embodiment of the invention, a two-part (2K) adhesive composition comprises:

a first portion comprising, based on the weight of the first portion:

40 to 75 wt%, preferably 47 to 68 wt% of (meth) acrylate ester monomer, wherein the (meth) acrylate ester monomer comprises at least one C of (meth) acrylic acid₁-C₆An alkyl ester;

6 to 16 wt%, preferably 10 to 13 wt%, of a copolymerizable acid, wherein the copolymerizable acid is selected from the group consisting of methacrylic acid, acrylic acid, itaconic acid, maleic acid, aconitic acid, crotonic acid, fumaric acid, and mixtures thereof; and

4 to 23 wt%, preferably 5 to 20 wt% of an electrolyte, wherein the electrolyte is selected from the group consisting of 1-ethyl-3-methylimidazolium mesylate, 1-ethyl-3-methylimidazolium methyl sulfate, and mixtures thereof; and

a second part comprising, based on the weight of the second part:

55 to 70 wt%, preferably 61 to 65 wt%, or 30 to 55 wt%, preferably 30 to 45 wt% of a first curing agent comprising or consisting of at least one free radical initiator that decomposes under the action of heat to provide free radicals;

0.03 to 1% by weight, preferably 0.05 to 0.3% by weight, of a second curing agent consisting of at least one compound which is a salt or complex of a transition metal selected from the group consisting of Fe, Co, V, Mn and Cu; and

28 to 40 wt.%, preferably 35 to 38 wt.%, of a solubilizer,

wherein the first part and/or the second part further comprises conductive particles selected from carbon black, silver and mixtures thereof.

Preferably, in this embodiment, the first curing agent is a peroxide or hydroperoxide compound selected from the group consisting of: t-butyl peroxide, t-butyl perbenzoate, cumene hydroperoxide, t-butyl peroxybenzoate, diacetyl peroxide, benzoyl peroxide, t-butyl peracetate, lauroyl peroxide and mixtures thereof: note that benzoyl peroxide is particularly preferred. Independently of or in addition to the preferred statements on the first curing agent, the second curing agent preferably comprises or consists of at least one iron-based compound selected from ferrocene, iron (II) acetylacetonate, iron (III) hexa (cyano-C) ferrate ammonium salt: note that ferrocene is particularly preferred.

Method and use

To form a defined two-part (2K) curable composition, the reactive parts are brought together and mixed in such a way as to cause hardening thereof. The reactive compounds should be mixed under sufficient shear to produce a homogeneous mixture. It is considered that this can be achieved without special conditions or special equipment. That is, suitable mixing devices may include: a static mixing device; a magnetic stir bar device; a whipper device; a screw conveyor; a batch mixer; a planetary mixer; brabender or C.W.

Form mixingA device; and high shear mixers such as blade mixers and rotating impellers.

For small-scale applications, which typically use volumes of less than 2 liters, the preferred packaging of the two-part (2K) composition would be a side-by-side double or coaxial cartridge, in which the two tubular chambers, typically of the same volume, are arranged side-by-side or inside each other and sealed with a piston: the driving of these pistons allows the parts to be advantageously extruded from the barrel through a tightly mounted static or dynamic mixer. For larger volume applications, two portions of the composition may be advantageously stored in drums or barrels: in this case, the two portions are extruded by a hydraulic press, in particular by a follower plate (follower plate), and fed through a pipe to a mixing device which ensures a fine and highly homogeneous mixing of the two portions. In any case, for any package, it is important that the parts are handled with an airtight and moisture-proof seal so that both parts can be stored for a long time, ideally 12 months or more.

Non-limiting examples of two-part dispensing apparatuses and methods that may be suitable for the present invention include those described in U.S. patent No. 6,129,244 and U.S. patent No. 8,313,006.

Depending on the desired properties of the cured composition, the two parts are typically mixed in a volume ratio of part a to part B of from 20:1 to 1:10, such as from 10:1 to 1:10, such as from 5:1 to 1:5, or such as from 2:1 to 1:2 or from 1.5:1 to 1: 1.5. The latter range includes a volume ratio of part a to part B of 1:1, which in itself represents a preferred embodiment of the present invention. Another preferred embodiment has a volume ratio of part a to part B of 10: 1. In some embodiments, the volume ratio of part a to part B may be 1: 12. In a highly preferred embodiment, the volume ratio of part a to part B is from 12:1 to 6.5: 1.

Where applicable, the two (2K) part curable composition should be broadly formulated to exhibit an initial viscosity at 25 ℃ of less than 200000 mPa-s, for example less than 100000 mPa-s, as determined immediately after mixing, for example within up to two minutes after mixing. Independently of or in addition to the viscosity characteristics, the two (2K) part composition should be formulated to be bubble free (foamed) upon mixing and subsequent curing.

According to the broadest method aspect of the present invention, the above-described composition is applied to one or more layers of material and then cured in situ. Prior to application of the composition, it is generally recommended to pretreat the relevant surfaces to remove foreign bodies therefrom: this step, if applicable, may facilitate subsequent adhesion of the composition thereto. Such treatments are known in the art and may be carried out in a single-stage or multi-stage manner, consisting for example of using one or more of the following treatments: an etching treatment with an acid suitable for the substrate and optionally an oxidizing agent; carrying out ultrasonic treatment; plasma treatment including chemical plasma treatment, corona treatment, atmospheric plasma treatment and flame plasma treatment; immersing in an aqueous alkaline degreasing bath; treating with an aqueous cleaning emulsion; treatment with a cleaning solvent, such as carbon tetrachloride or trichloroethylene; and water rinsing, preferably with deionized water or demineralized water. In those cases where an aqueous alkaline degreasing bath is used, any residual degreaser on the surface should be removed by rinsing the substrate surface with deionized or softened water.

The composition is then applied to the pretreated surface of the substrate by conventional application methods such as: brushing; roll coating, for example, roll coating using a 4 application roll apparatus in which the composition does not contain a solvent or a 2 application roll apparatus for a composition containing a solvent; applying by a scraper method; a printing method; and spray coating methods including, but not limited to, air atomized spray, air assisted spray, airless spray, and high volume low pressure spray.

As described above, the present invention provides an adhesive structure comprising: a first layer of material having a conductive surface; and a second layer of material having an electrically conductive surface, wherein a cured debondable two part (2K) adhesive composition as defined above and in the appended claims is disposed between the first and second layers of material. To create such a structure, the adhesive composition may be applied to at least one inner surface of the first and/or second material layer, and then the two layers are subsequently contacted such that the curable and debondable adhesive composition according to the present disclosure is disposed between the two layers.

It is recommended that the composition be applied to the surface at a wet film thickness of 10 to 500 μm. Applying thinner layers in this range is more economical and reduces the likelihood of detrimental thick cured areas. However, tight control must be exercised in applying thinner coatings or layers to avoid the formation of a discontinuous cured film.

The curing of the application compositions of the invention generally takes place at temperatures in the range from 40 ℃ to 200 ℃, preferably from 50 ℃ to 175 ℃, in particular from 75 ℃ to 175 ℃. The appropriate temperature depends on the particular compound present and the desired cure rate and can be determined by the skilled person in individual cases, using simple preliminary tests if necessary. Of course, lower temperature curing in the above range is advantageous because it avoids the need to sufficiently heat or cool the mixture from the typically most common ambient temperature. However, where applicable, the temperature of the mixture formed from the individual parts of the two (2K) part composition may be raised above the mixing temperature and/or application temperature using conventional means including microwave induction.

Drawings

The invention will be described with reference to the accompanying drawings, in which:

fig. 1a shows an adhesive structure according to a first embodiment of the invention.

Fig. 1b shows an adhesion structure according to a second embodiment of the present invention.

Fig. 2a shows the initial debonding of the structure of the first embodiment when a current is passed through the structure.

Fig. 2b shows the initial debonding of the structure of the second embodiment when current is passed through the structure.

Fig. 3a and 3b show the results of lap shear strength testing of stainless steel substrates bonded with a cured adhesive composition according to an embodiment of the invention.

Fig. 4a and 4b show the results of lap shear strength testing of aluminum substrates bonded with a cured adhesive composition according to an embodiment of the invention.

Figures 5a and 5b show the stability results over time.

As shown in the attached fig. 1a, a bonding structure is provided in which a cured adhesive layer (10) is disposed between two conductive substrates (11). A layer of non-conductive material (12) may be provided on the conductive substrate (11) to form a more complex adhesive structure as shown in figure 1 b. The conductive substrate (11) of each layer is in electrical contact with a power source (13), which power source (13) may be a battery or an alternating current (ac) driven Direct Current (DC) power source. The positive and negative terminals of the power supply (13) are shown in a fixed position, but those skilled in the art will of course recognize that the polarity of the system may be reversed.

The two electrically conductive substrates (11) are shown in the form of layers which may consist in particular of the following materials: a metal film; a metal plate; a metal mesh or grid; deposited metal particles; a resin material having conductivity by a conductive element provided therein; alternatively, a conductive oxide layer. As exemplary conductive elements, silver wire, single-walled carbon nanotubes and multi-walled carbon nanotubes may be mentioned. As exemplary conductive oxides, mention may be made of: doped indium oxide, such as Indium Tin Oxide (ITO); doped zinc oxide; antimony tin oxide; cadmium stannate; and zinc stannate. In addition to the selection of the conductive material, one skilled in the art will recognize that in the case where the conductive substrate (11) is in the form of a grid or mesh that provides limited contact with the cured adhesive layer (10), the effectiveness of the debonding operation may be reduced.

When a voltage is applied between each of the conductive substrates (11), a current is supplied to the adhesive composition (10) disposed therebetween. This initiates an electrochemical reaction at the interface of the substrate (11) and the binder composition, which is understood to be an oxidation reaction at a positively charged interface or anode interface and a reduction reaction at a negatively charged interface or cathode interface. This reaction is believed to weaken the adhesive bond between the substrates, allowing the debondable composition to be easily removed from the substrates.

As shown in fig. 2a and 2b, debonding occurs at the positive electrode interface, i.e., the interface between the binder composition (10) and the conductive surface (11) in electrical contact with the positive electrode. By reversing the direction of the current flow before separating the substrates, the adhesive bond at the interface of the two substrates can be weakened.

It should be noted, however, that the composition of the adhesive layer (10) may be adjusted so that debonding occurs at or from the positive or negative interface. For some embodiments, a voltage applied across both surfaces to form an anode interface and a cathode interface will cause debonding to occur at both the anode and cathode binder/substrate interfaces. In an alternative embodiment, if the composition is not responsive to direct current at both interfaces, then reverse polarity may be used to simultaneously debond both substrate/adhesive interfaces. The current may be applied in any suitable waveform provided that sufficient total time is allowed for debonding at each polarity. In this regard, sine waves, rectangular waves, and triangular waves may be suitable and may be applied from a controlled voltage source or a controlled current source.

Without intending to limit the invention, it is believed that the debinding operation can be effectively performed in the event that at least one and preferably both of the following conditions occur: a) an applied voltage of 0.5 to 100V; and, b) voltage application for a duration of 1 second to 60 minutes. If the release of the conductive substrate from the cured adhesive is facilitated by the application of force (e.g., by a weight or spring), it may only take on the order of a few seconds to apply the electrical potential. In some embodiments, a potential of 5V for 10 minutes is sufficient to have a debonding effect, while in some embodiments a potential of 3.5V for 30 minutes is sufficient.

Desirably, the adhesive composition is only on the first substrate or the second substrate after debonding, meaning that one of the substrates is substantially free of adhesive.

The following examples are illustrative of the present invention and are not intended to limit the scope of the invention in any way.

Examples

The following materials were used in the examples:

aerosil 200: hydrophilic fumed silica, available from Evonik Industries.

XT 100: core shell tougheners (methyl methacrylate-butadiene-styrene, MBS), available from Arkema Inc.

1-ethyl-3-methylimidazolium mesylate: available from TCI America Inc.

Ferrocene: bis (. eta.5-cyclopentadienyl) iron, available from Sigma Aldrich.

DER 331: bisphenol A epoxy resin, available from Dow Chemical.

Benzoyl peroxide (75%): powder, available from Arkema Inc.

Example 1

Parts (a) and (B) of composition 1 were prepared according to table 1 below.

TABLE 1

Equal parts by weight (A, B) were loaded into separate compartments of a 50g cartridge and sealed at both ends. The cartridge is then loaded into the cartridge gun and the mixing tip is mounted at the front end. Both parts are pushed into the mixing tip by applying a constant pressure on the trigger to ensure adequate mixing prior to application to the substrate.

The substrates were copper (thickness 1mm), aluminum (AA6016, thickness 1.25mm), and stainless steel (1.4301, thickness 1.5mm) each having a thickness, and the base materials were cut into a size of 2.5cm × 10cm (1"× 4") for the tensile test.

The Tensile Lap Shear (TLS) test was performed according to the test method described on page 5.

The applied two-part (2K) adhesive composition was cured in the overlapping area by applying a temperature of 100 ℃ for 30 minutes. Subsequently, the samples were stored in a climate chamber at 25 ℃ and 20% humidity.

For each substrate, tensile lap shear strength was studied after the storage period and after a constant potential of 75V was applied to the adhesive layer for a duration of 1 hour. The results are reported in table 2 below.

TABLE 2

Base material	Initial adhesive Strength (MPa)	Adhesive Strength (MPa) after 75V lasted for 1 hour
			Copper (Cu)	2.5(±0.13)	0.95(±0.21)
Aluminium	15.99(±1.16)	2.08(±0.63)
			Stainless steel	17.31(±3.31)	0.06(±0.03)

For adhesively bonded stainless steel substrates, lap shear strength (MPa) was investigated under the following two conditions: a) applying a constant potential (75V) across the overlapping adhesive region over a period of 20 minutes; and, b) applying a different potential across the overlapping adhesive regions for a fixed period of time (10 minutes). The results of these studies are given in the appended figures 3a and 3 b.

For adhesively bonded aluminum substrates, lap shear strength (MPa) was studied under the following two conditions: a) applying a constant potential (75V) across the overlapping adhesive region over a period of 20 minutes; and, b) applying a different potential across the overlapping adhesive regions for a fixed period of time (10 minutes). The results of these studies are given in the appended figures 4a and 4 b.

Example 2

Parts (a) and (B) of composition 2 were prepared according to table 3 below. Composition 2 was prepared and tested according to the method described in example 1.

TABLE 3

For each substrate, tensile lap shear strength was studied after the storage period and after a constant potential of 75V was applied to the adhesive layer for a duration of 1 hour. The results are reported in table 4 below.

TABLE 4

Base material	Initial adhesive Strength (MPa)	Adhesive Strength (MPa) after 75V for 1 hour
			Aluminium	13.96(±0.65)	2.26(±0.42)
Stainless steel	20.81(±0.65)	0.54(±0.1)

Example 3

Parts (a) and (B) of composition 3 were prepared according to table 5 below. Composition 3 was prepared and tested according to the method described in example 1.

TABLE 5

For the substrates, the tensile lap shear strength was investigated after the storage period and after a constant potential of 75V was applied on the adhesive layer for a duration of 1 hour. The results are reported in table 6 below.

TABLE 6

Substrate material	Initial adhesive Strength (MPa)	Adhesive Strength (MPa) after 75V for 1 hour
			Aluminium	11.94(±0.5)	5.94(±)

Example 4

Parts (a) and (B) of composition 4 were prepared according to table 7 below. Composition 4 was prepared and tested according to the method described in example 1.

TABLE 7

For each substrate, tensile lap shear strength was studied after the storage period and after a constant potential of 75V was applied to the adhesive layer for a duration of 1 hour. The results are reported in table 8 below.

TABLE 8

Base material	Initial adhesive Strength (MPa)	Adhesive Strength (MPa) after 75V lasted for 1 hour
			Aluminium	4.47(±1.09)	0.044(±)

Example 5

Parts (a) and (B) of composition 5 were prepared according to table 9 below. Composition 5 was prepared and tested according to the method described in example 1.

TABLE 9

For each substrate, tensile lap shear strength was studied after the pot life and after a constant potential of 75V was applied to the adhesive layer for a duration of 1 hour. The results are reported in table 10 below.

Watch 10

Base material	Initial adhesive Strength (MPa)	Adhesive Strength (MPa) after 75V lasted for 1 hour
			Aluminium	14.58(±0.59)	3.86(±0.63)

In view of the foregoing description and examples, it will be evident to a person skilled in the art that equivalent modifications may be made thereto without departing from the scope of the claims.

Example 6

The composition of example 1 was subjected to a stability test. For this test, standard lap shear samples were prepared and cured at 100 ℃ for 30 minutes. Aluminum and steel substrates were used. Subsequently, the samples were stored in a climate chamber at 25 ℃ and 20% humidity. Lap shear was measured after 1 day, 7 days, 14 days, 28 days, 60 days and 90 days. The results are reported in tables 11 and 12 below.

TABLE 11

Aluminium	Initial adhesive Strength (MPa)	Adhesive Strength (MPa) after 75V for 1 hour
			1 day	13.87+/–1.49	2.1+/–0.78
7 days	14.26+/–0.35	2+/–0.37
			14 days	15.5+/–1.16	2.74+/–1.05
28 days	15.99+/–1.16	2.44+/–0.96
			60 days	15.69+/–0.9	1.93+/–0.93

TABLE 12

Stainless steel	Initial adhesive Strength (MPa)	Adhesive Strength (MPa) after 75V for 1 hour
			1 day	15.74+/–1.27	0.2
7 days	13.34+/–3.31	0.1+/–0.11
			14 days	14.42+/–2.77	0.08+/–0.11
28 days	18.39+/–2.71	0.046+/–0.07
			60 days	12.76+/–0.74	0.08+/–0.01
90 days	17.61+/–3.39	0

The stability results are shown in figures 5a and 5 b. Fig. 5a shows the adhesion properties and debonding effect for aluminum, while fig. 5b shows the same effect for stainless steel. The test results show that the compositions according to the invention have good initial adhesion properties and do not lose them over time. Furthermore, the compositions according to the invention have a good initial debonding effect and remain over time.

Example 7

Parts (a) and (B) of compositions 6a and 6B were prepared according to table 13 below. Compositions 6a and 6b were prepared and tested according to the method described in example 1.

Watch 13

For the substrates, the tensile lap shear strength was studied after the storage period and after a constant potential of 75V was applied on the adhesive layer for a duration of 20 minutes. The results are reported in table 14 below. The test results are shown in fig. 6.

TABLE 14

Base material AA6016	Initial adhesive Strength (MPa)	Adhesive Strength (MPa) after 75V for 20 minutes
			Composition
6a	18.19(±1.3)	5.19(±1.9)
			Composition 6b	10.38(±2.2)	0.64(±)

Example 8

Composition 7 was prepared according to table 15 below. It should be noted that the composition is free of methacrylic acid, otherwise the composition is according to the invention.

Watch 15

Composition 7 did not cure and the electrolyte separated from the composition.

Example 9

Compositions 8a, 8b and 8c were prepared according to table 16 below.

TABLE 16

For the substrates, the tensile lap shear strength was investigated after the pot life and after a constant potential of 75V was applied on the adhesive layer for a duration of 20 minutes. Here the results are recorded in table 17 below, and furthermore, the test results are shown in fig. 7.

TABLE 17

Base material AA6016	Initial bond strength	Adhesive strength after 75V for 20 minutes
			Composition
8a	15.19(±0.86)	10.69(±0.74)
			Composition 8b	11.94(±0.5)	5.93(±2.27)
Composition 8c	16.92(±0.46)	15.44(±0.28)

Example 10

Compositions 9a, 9b and 9c were prepared here according to table 18 below.

Watch 18

For the substrates, the tensile lap shear strength was studied after the storage period and after a constant potential of 75V was applied on the adhesive layer for a duration of 20 minutes. The results are reported in table 19 below.

Watch 19

Base material AA6016	Initial adhesive Strength (MPa)	Adhesive Strength (MPa) after 75V for 20 minutes
			Composition 9a	7.59(±1.48)	3.6(±1.33)
Composition 9b	10.16(±1.11)	4.73(±2.06)
			Composition 9c	11.82(±0.29)	4.55(±1.55)
Composition 8c	16.92(±0.46)	15.44(±0.28)

Example 11

Different electrolyte concentrations were tested. Compositions 10a, 10b, 10c, 10d and 10e were prepared according to table 20 below.

Watch 20

For the substrates, the tensile lap shear strength was studied after the storage period and after a constant potential of 30V was applied on the adhesive layer for a duration of 20 minutes. The results are reported in table 21 below. The test results are shown in fig. 8.

TABLE 21

Base material AA6016	Initial bond strength	Adhesive strength after 75V for 20 minutes
			Composition
10a	17.41(±1.04)	7.66(±3.29)
			Composition 10b	16.09(±1.17)	4.13(±0.22)
Composition 10c	16.28(±1.37)	1.84(±0.84)
			Composition 10d	13.03(±0.93)	1.43(±0.34)
Composition 10e	12.12(±2.24)	0.98(±0.37)

Example 12

Different toughener and core shell particle concentrations showed improvements in T-peel and aging test (90% Rh) impact, stability and LSS values. Compositions 11a, 11b, 11c, 11d and 11e were prepared according to table 22 below.

For the substrates, the tensile lap shear strength was studied after the storage period and after a constant potential of 30V was applied on the adhesive layer for a duration of 20 minutes. The results are reported in table 23 below.

TABLE 23

Base material AA6016	Initial bond strength	75V for 20 minLater adhesive strength
			Composition
11a	10.54(±1.5)	0.54(±0.24)
			Composition 11b	15.28(±0.86)	5.38(±0.51)
Composition 11c	15.33(±1.37)	2.34(±0.3)
			Composition 11d	14(±0.35)	5.12
Composition 11e	16.55(±0.07)	5.5(±0.4)

Table 24 below shows the Lap Shear Strength (LSS) test results, which are also illustrated in fig. 9.

TABLE 24

Base material AA6016	Wedge impact test (ISO 11343)	Peel strength (STM 710)
			Composition 11a	1.15(±1.31)	0
Composition 11b	12.8(±2.8)	2.38
			Composition 11c	1.63(±0.99)	2.39
Composition 11d	1.05(±0.06)	3.45
			Composition 11e	9.46(±0.84)	2.44

Claims (17)

1. A curable and debondable two-part adhesive composition comprising:

a first portion comprising:

(meth) acrylate ester monomers;

a copolymerizable acid; and

an electrolyte; and

a second part comprising:

a first curing agent for the first part of monomers;

a second curing agent for the first part of monomers; and

a solubilizer.

2. The curable and debondable two-part adhesive composition according to claim 1, wherein the (meth) acrylate monomer is selected from the group consisting of: methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, t-butyl (meth) acrylate, n-pentyl (meth) acrylate, n-hexyl (meth) acrylate, cyclohexyl (meth) acrylate, n-heptyl (meth) acrylate, n-octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, nonyl (meth) acrylate, decyl (meth) acrylate, dodecyl (meth) acrylate, phenyl (meth) acrylate, tolyl (meth) acrylate, benzyl (meth) acrylate, 2-methoxyethyl (meth) acrylate, 3-methoxybutyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, t-butyl (meth) acrylate, n-pentyl (meth) acrylate, n-hexyl (meth) acrylate, cyclohexyl (meth) acrylate, n-heptyl (meth) acrylate, n-octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, n-butyl (meth) acrylate, n-butyl acrylate, n, Octadecyl (meth) acrylate, glycidyl (meth) acrylate, isobornyl (meth) acrylate, 2-aminoethyl (meth) acrylate, y- (meth) acryloyloxypropyltrimethoxysilane, ethylene oxide (meth) acrylate adduct, trifluoromethyl (meth) acrylate, 2-trifluoroethyl (meth) acrylate, 2-perfluoroethyl-2-perfluorobutylethyl (meth) acrylate, 2-perfluoroethyl (meth) acrylate, perfluoromethyl (meth) acrylate, diperfluoromethylmethyl (meth) acrylate, 2-perfluoromethyl-2-perfluoroethylmethyl (meth) acrylate, 2-perfluorohexylethyl (meth) acrylate, 2-perfluorodecylethyl (meth) acrylate, 2-perfluorohexadecylethyl (meth) acrylate, isobornyl (meth) acrylate, 2-perfluorohexadecylethyl (meth) acrylate, and mixtures thereof, Ethoxylated trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, dipentaerythritol monohydroxypentaacrylate, pentaerythritol triacrylate, ethoxylated trimethylolpropane triacrylate, 1, 6-hexanediol diacrylate, neopentyl glycol diacrylate, pentaerythritol tetraacrylate, 1, 2-butanediol diacrylate, ethoxylated trimethylolpropane tri (meth) acrylate, propoxylated glycerol tri (meth) acrylate, trimethylolpropane tri (meth) acrylate, dipentaerythritol monohydroxypenta (meth) acrylate, tripropylene glycol di (meth) acrylate, propoxylated neopentyl glycol di (meth) acrylate, 1, 4-butanediol di (meth) acrylate, polyethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, ethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, ethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, ethylene glycol di (meth) acrylate, and (meth) acrylate, Butanediol di (meth) acrylate, ethoxylated bisphenol A di (meth) acrylate and mixtures thereof,

preferably, the (meth) acrylate monomer is selected from the group consisting of methyl methacrylate, methyl acrylate, ethyl methacrylate, ethyl acrylate, isobornyl methacrylate, isobornyl acrylate, ethoxylated trimethylolpropane triacrylate, and mixtures thereof.

3. The curable and debondable two part adhesive composition according to claim 1 or 2, wherein the (meth) acrylate ester monomer component is present in an amount of from 20 to 80 wt. -%, preferably from 40 to 75 wt. -%, more preferably from 47 to 68 wt. -%, even more preferably from 53 to 60 wt. -%, based on the total weight of the first part.

4. The curable and debondable two part adhesive composition according to any one of claims 1 to 3, wherein the copolymerizable acid is selected from methacrylic acid, acrylic acid, itaconic acid, maleic acid, aconitic acid, crotonic acid, fumaric acid and mixtures thereof, preferably the copolymerizable acid is methacrylic acid.

5. A curable and debondable two part adhesive composition according to one of claims 1 to 4, wherein the copolymerizable acid is present in an amount of from 0.25 to 20 wt. -%, preferably from 6 to 16 wt. -%, more preferably from 10 to 13 wt. -%, based on the total weight of the first part.

6. The curable and debondable two-part adhesive composition according to any one of claims 1 to 5, wherein the electrolyte is selected from the group consisting of 1-ethyl-3-methylimidazolium methanesulfonate, 1-ethyl-3-methylimidazolium methylsulfate, 1-hexyl-3-methylimidazolium 2- (2-fluoroanilino) -pyridinium, 1-hexyl-3-methylimidazolium imide, 1-butyl-1-methyl-pyrrolidinium 2- (2-fluoroanilino) -pyridinium, 1-butyl-1-methyl-pyrrolidinium imide, trihexyl (tetradecyl) phosphonium 2- (2-fluoroanilino) -pyridinium, cyclohexyltrimethylammonium bis (trifluoromethylsulfonyl) imide, bis (2-hydroxyethyl) ammonium trifluoroacetate, N-dimethyl (2-hydroxyethyl) ammonium octanoate, methyltrioctylammonium bis (trifluoromethylsulfonyl) imide, N, N-Ethyl-N-N-N-tetramethylguanidine trifluoromethanesulfonate, guanidine trifluoromethanesulfonate, 1-butyl-4-methylpyridinium bromide, 1-butyl-3-methylpyridinium tetrafluoroborate, 1-butyl-3-hydroxymethylpyridinium ethyl sulfate, 1-butyl-1-methylpyrrolidinium bis (trifluoromethylsulfonyl) imide, 1-butyl-methylpyrrolidinium tris (pentafluoroethyl) trifluorophosphate, 3-methylimidazolium ethyl sulfate, 1-ethyl-3-methylimidazolium chloride, 1-ethyl-3-ethyl-methylimidazolium bromide, 1-butyl-3-methylimidazolium chloride, 1-hexyl-3-methylimidazolium chloride, 1-octyl-3-methylimidazolium chloride, 1-methyl-3-octylimidazolium chloride, 1-propyl-3-methylimidazolium iodide, 1-butyl-3-methylimidazolium tetrafluoroborate, 1-butyl-3-methylimidazolium trifluoromethanesulfonate, 1-butyl-3-methylimidazolium hexafluorophosphate, 1-butyl-2, 3-dimethylimidazolium tetrafluoroborate, 1-butyl-2, 3-dimethylimidazolium hexafluorophosphate, 1-butylimidazole, 1-methylimidazolium tetrafluoroborate, tetrabutylphosphonium tris (pentafluoroethyl) trifluorophosphate, trihexyl (tetradecyl) phosphonium tetrafluoroborate and mixtures thereof,

preferably selected from the group consisting of 1-ethyl-3-methylimidazolium methanesulfonate, 1-ethyl-3-methylimidazolium methylsulfate and mixtures thereof.

7. A curable and debondable two part adhesive composition according to one of claims 1 to 6, wherein the electrolyte is present in an amount of from 2.5 to 25 wt. -%, preferably from 4 to 23 wt. -%, more preferably from 5 to 20 wt. -%, based on the total weight of the first part.

8. The curable and debondable two-part adhesive composition according to one of claims 1-7, wherein the first curing agent is a peroxide curing agent,

the peroxide curing agent is preferably selected from the group consisting of t-butyl peroxide, t-butyl perbenzoate, cumene hydroperoxide, t-butyl peroxybenzoate, diacetyl peroxide, benzoyl peroxide, t-butyl peracetate, lauroyl peroxide, and mixtures thereof,

more preferably, the peroxide curative is benzoyl peroxide.

9. The curable and debondable two-part adhesive composition according to any one of claims 1 to 8, wherein the first curing agent is present in an amount of from 25 to 75 wt. -%, based on the total weight of the second part.

10. A curable and debondable two-part adhesive composition according to any one of claims 1 to 9, wherein the second curing agent is a metal compound selected from salts and complexes of iron, copper, cobalt, vanadium and manganese, preferably an iron-based compound selected from ferrocene, iron (II) acetylacetonate, iron (III) ammonium hexa (cyano-C) ferrate and mixtures thereof.

11. A curable and debondable two-part adhesive composition according to one of claims 1 to 10, wherein the second curing agent is present in an amount of from 0.01 to 5 wt. -%, preferably from 0.03 to 1 wt. -%, more preferably from 0.05 to 0.3 wt. -%, based on the total weight of the second part.

12. The curable and debondable two-part adhesive composition according to one of claims 1 to 11, wherein the solubilizing agent is polyethylene glycol or an epoxy resin selected from the group consisting of: cycloaliphatic epoxides, epoxy novolac resins, bisphenol a epoxy resins, bisphenol F epoxy resins, bisphenol a epichlorohydrin based epoxy resins, alkyl epoxides, limonene dioxide, polyepoxides, and mixtures thereof; the solubilizer is preferably a bisphenol a epoxy resin.

13. The curable and debondable two part adhesive composition according to any one of claims 1 to 12, wherein the solubilizing agent is present in an amount of from 20 to 45 wt. -%, preferably from 28 to 40 wt. -%, more preferably from 35 to 38 wt. -%, based on the total weight of the second part.

14. The curable and debondable two-part adhesive composition according to one of claims 1 to 13, wherein the first part and/or the second part further comprises conductive particles selected from carbon black, silver and mixtures thereof.

15. An adhesive structure, comprising:

a first layer of material having a conductive surface; and

a second layer of material having a conductive surface;

wherein the cured debondable two-part adhesive composition according to one of claims 1 to 14 is disposed between the first and second material layers.

16. A method of debonding the adhesive structure of claim 15, the method comprising the steps of:

i) applying a voltage across the two surfaces to form an anode interface and a cathode interface; and

ii) debonding the surface.

17. The method according to claim 16, wherein the voltage applied in step i) is between 0.5 and 100V, and preferably between 1 second and 60 minutes.

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